In which of the following situations is specific performance available as a remedy? 

(a) Mary and Anne enter into a written agreement under which Mary agrees to sell and Anne agrees to buy for ten dollars per share 100 shares of the 300 shares outstanding of the capital stock of the Infinitesimal Steel Corporation, whose shares are not listed on any exchange and are closely held. Mary refuses to deliver when tendered the $1,000.

(b) Modifying (a) above, assume that the subject matter of the agreement is stock of the United States Steel Corporation, which is traded on the New York Stock Exchange. 

(c) Modifying (a) above, assume that the subject matter of the agreement is undeveloped farmland of little commercial value.